I also have the Huma 12fpe regulator kit. There's not that much info out there besides Wingman's (AirBorne Arms) YouTube video. I did get 2 valves, one to cut and the other in case I messed up. The only issue I'm having is with the Huma 12fpe hammer spring that comes with. It's a couple coils too long compared to the factory hammer spring and I'm wondering if I should cut it. It would like to get a spare first just in case.
When I install the 12fpe HS, the hammer sticks out of the breach face about the same length because of the longer coils. After installing it, I noticed that it chipped some of the anodizing around the valve pin area.
I have a sub-12 hammer spring installed and also have an extra sub-12 spring. I just compared it to the original hammer spring that I pulled out of my Leshiy and the sub-12 spring is longer.
I vaguely remember noticing this back then but am not sure if was as significant as the two I just looked at. It probably was but I went forth with installing it.
What I do not recall is if the hammer protruded with the original hammer spring. It certainly protrudes now.
However, I do not have any chipping around the valve area like your pictures show.
Based on your picture I probably cut the plastic end of the poppet a bit longer than yours. Not sure if yours is too short or not.